厚度对HVOF喷涂WC-12Co涂层结构的影响

利用HVOF制备了WC-12C0涂层,喷涂原始粉末为微纳米复合粉,涂层的厚度分别为0.5,1,2,3,4 mm。采用扫描电镜(SEM)、X射线衍射仪(XRD)分析了涂层的显微结构和相组成,并对涂层的孔隙率进行了测量。结果表明,厚度对涂层的表面形貌与表面粗糙度无明显的影响,但对截面显微结构有较大影响,厚度小于1 mm的涂层沿厚度方向显微结构无明显变化,而厚度大于1 mm的涂层中部组织比较致密,孔隙率小,涂层与基体结合区域及近表面区域组织较为疏松。所有涂层均出现了分解与脱碳,涂层越厚分解越严重,出现的W_2C和Co_3W_3C相越多。

Effect of Thickness on Microstructure of HVOF Sprayed WC-12Co Coatings

WC-12Co coatings were sprayed by HVOF with a composite mixture of microstructure and nanostructure powder. The thickness of the coatings are 0.5mm, 1mm, 2mm, 3mm and 4mm respectively.SEM and XRD were used to analyse the microstructure and phase composition of the coatings. Porosity of the coatings was also tested. Results show that thickness has little influence on surface microstrucure and roughness of the coating, on the contrary, thickness has great influence on section microstrucure. For coating which is thicker than 1mm, microstructure of the middle part of the coating is denser than the interfacial and the upper area, however, microstructure changes litte along the deposition direction for coating which is thinner than 1mm. There are few W2C and Co3W3C phase in the coating for thermal decomposition of WC, furthermore, more and more decompostion occurs with the increase of the coating thickness.